First solution of pretty clear. Here is one interesting thread which you people may find useful. Very old thread, but having good discussion.
Read this area.
Internet Explorer supports DHTML behaviors. does not mean server control. You can create client DHTML component that has namespace and will run on the client machine. Also, namespaces are allowed in XHTML and techically you can use asp namespace for something else on a client, if you wish. Runat="server" prevents namespace clash. If element has no runat="server" attribute, it will be sent to the client browser unchanged. Therefore, you can use HTML components (HTCs) in ASP.NET pages as well